<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        /*交集选择器，两个选择器连在一起*/
        p.box {
            color: red;
        }
    </style>
</head>
<body>
<div>
    <p class="box">p.box</p>
    <p>p</p>
    <div class="box">
        div.box
    </div>
</div>
</body>
</html>